Insulating substrates are often used as circuit carriers for electrical circuits and, for example in order to produce a power semiconductor module, are soldered onto a carrier by means of a large-area soldered connection. In general, the insulating substrates are joined together from two or more component parts. Depending on the course of the joining process in question and the (generally different) coefficients of thermal expansion of the component parts, the circuit carrier may have a temperature-dependent curvature which is predictable only with difficulty. Two substrates of identical structure could exhibit a different temperature-dependent curvature behavior even when they were supposedly produced by the same production method and with the same process parameters and accordingly should in actual fact exhibit an identical temperature-dependent curvature behavior. The unpredictability of the temperature-dependent curvature behavior has the effect that the thickness or the thickness distribution of the solder used for soldering the insulating substrate onto the carrier is also not predictable. This can have the effect, for example, that the solder has a locally increased thickness in a region in which the circuit carrier is populated with a power semiconductor chip. This is associated with a locally increased thermal contact resistance between the insulating substrate and the carrier, this being disadvantageous if the process heat which arises in the power semiconductor chip is to be dissipated via the insulating substrate and the solder to the carrier.
If a solder layer with a greatly inhomogeneous thickness distribution was considered to be disadvantageous for a specific structure, an examination by X-ray was required following production of the joint, this being associated with a high level of expenditure. If the examination established an excessively inhomogeneous thickness distribution of the solder layer, it was necessary to dispose of, or expensively refurbish, the assembly comprising the carrier and the insulating substrate, and if appropriate also comprising electronic components with which the insulating substrate is populated.